Doctors have known for a long time that alcoholism is associated with increased risk of anxiety, such as PTSD (post traumatic stress disorder), and that heavy drinkers are more likely to be involved in automobile accidents and/or domestic violence situations.
Now, new research by experts at the National Institute on Alcohol Abuse and Alcoholism (NIAAA) and UNC's Bowles Center for Alcohol Studies, published online September 2, 2012 in Nature Neuroscience has determined that high alcohol consumption rewires brain circuitry, which suggests that it is more difficult for people who drink heavily to bounce back from a traumatic event in their lives.
Thomas Kash, PhD, assistant professor of pharmacology at the University of North Carolina School of Medicine commented: "There's a whole spectrum to how people react to a traumatic event. It's the recovery that we're looking at - the ability to say 'this is not dangerous anymore.' Basically, our research shows that chronic exposure to alcohol can cause a deficit with regard to how our cognitive brain centers control our emotional brain centers."
Senior author of the study Andrew Holmes, PhD, said:
"A history of heavy alcohol abuse could impair a critical mechanism for recovering from a trauma, and in doing so put people at greater risk for PTSD . The next step will be to test whether our preclinical findings translate to patients currently suffering from comorbid PTSD and alcohol abuse. If it does, then this could lead to new thinking about how we can better treat these serious medical conditions."
For their trial, the experts split mice into two groups. The first was given the equivalent amount of alcohol for humans that is twice the limit allowed for driving. The second was not given any alcohol at all. The mice were then taught by use of small shocks to be scared of a certain sound the researchers played.
The researchers observed that when the sound played over and over without the shock, the mice who were in the no alcohol group eventually stopped being scared of the tone. On the other hand, the mice who had high exposure to alcohol were scared of the noise, making them stand completely motionless every time they heard it - for a long time after the shocks were not present.
The authors explain that these findings are very much like the ones seen in individuals who suffer from PTSD, with these people taking longer to get over a certain fear even when the situation is not one that they should be scared of anymore.
They believe that this evidence stems back to the neural circuitry of the mice that were chronically exposed to alcohol. When analyzing the brains of the two different groups of mice, the researchers found that the nerve cells found in the prefrontal cortex of the brains of the mice who had been exposed to alcohol, were shaped differently than the mice who had not been exposed to any alcohol. They also noticed that NMDA, an important receptor in the brain was not as active in the mice who consumed alcohol.
According to Holmes, this newly found evidence is important because they were able to determine what part was being harmed by the alcohol, resulting in troubles getting over fear.
"We're not only seeing that alcohol has detrimental effects on a clinically important emotional process, but we're about to offer some insight into how alcohol might do so by disrupting the functioning of some very specific brain circuits."
The researchers note that the findings will make way for the development of new treatments to assist patients with anxiety disorders and high alcohol consumption.
Kash concludes: "This study is exciting because it gives us a specific molecule to look at in a specific brain region, thus opening the door to discovering new methods to treat these disorders."
Written by Christine Kearney